The Diocese of Fort Portal was created by Pope John XXIII on April 19th, 1961 together with the appointment of Rt. Rev. Vincent Joseph McCauley CSC, now Servant of God as its first Bishop. The Diocese was detached from Mbarara Diocese which up to 1953 was Rwenzori Vicariate.  The founding of Fort Portal Diocese was a fruit of the missionary work of the Missionaries of Africa, also known as the White Fathers and the Missionary activity of Fr. Augustine Achte (Pere Akiti) who introduced the Catholic faith in Tooro.

When Pope Paul VI visited Uganda in 1969, he ordained among others Bishop Serapio B. Magambo, Auxiliary Bishop of Fort Portal on 1st August 1969.  Bishop Magambo took Canonical possession of the Diocese of Fort Portal as its Ordinary on 1st January 1972.
Bishop Serapio B. Magambo was succeeded by Bishop Paul L. Kalanda then the Bishop of Moroto.  He was appointed to the See of Fort Portal on 28th August 1991 and was installed as Ordinary, taking Canonical possession of the Diocese on 3rd November 1991.